Posts tagged gender
Articles and news from the latest research reports.
The human body produces chemical cues that communicate gender to members of the opposite sex, according to researchers who report their findings in the Cell Press journal Current Biology on May 1. Whiffs of the active steroid ingredients (androstadienone in males and estratetraenol in females) influence our perceptions of movement as being either more masculine or more feminine. The effect, which occurs completely without awareness, depends on both our biological sex and our sexual orientations.
"Our findings argue for the existence of human sex pheromones," says Wen Zhou of the Chinese Academy of Sciences. "They show that the nose can sniff out gender from body secretions even when we don’t think we smell anything on the conscious level."
Earlier studies showed that androstadienone, found in male semen and armpits, can promote positive mood in females as opposed to males. Estratetraenol, first identified in female urine, has similar effects on males. But it wasn’t clear whether those chemicals were truly acting as sexual cues.
In the new study, Zhou and her colleagues asked males and females, both heterosexual and homosexual, to watch what are known as point-light walkers (PLWs) move in place on a screen. PLWs consist of 15 dots representing the 12 major joints in the human body, plus the pelvis, thorax, and head. The task was to decide whether those digitally morphed gaits were more masculine or feminine.
Individuals completed that task over a series of days while being exposed to androstadienone, estratetraenol, or a control solution, all of which smelled like cloves. The results revealed that smelling androstadienone systematically biased heterosexual females, but not males, toward perceiving walkers as more masculine. By contrast, the researchers report, smelling estratetraenol systematically biased heterosexual males, but not females, toward perceiving walkers as more feminine.
Interestingly, the researchers found that homosexual males responded to gender pheromones more like heterosexual females did. Bisexual or homosexual female responses to the same scents fell somewhere in between those of heterosexual males and females.
"When the visual gender cues were extremely ambiguous, smelling androstadienone versus estratetraenol produced about an eight percent change in gender perception," Zhou says, a statistically very significant effect.
"The results provide the first direct evidence that the two human steroids communicate opposite gender information that is differentially effective to the two sex groups based on their sexual orientation," the researchers write. "Moreover, they demonstrate that human visual gender perception draws on subconscious chemosensory biological cues, an effect that has been hitherto unsuspected."
Gender influences symptoms of genetic disorder
A genetic disorder that affects about 1 in every 2,500 births can cause a bewildering array of clinical problems, including brain tumors, impaired vision, learning disabilities, behavioral problems, heart defects and bone deformities. The symptoms and their severity vary among patients affected by this condition, known as neurofibromatosis type 1 (NF1).
Image caption: A mutation in the gene that causes a human condition, neurofibromatosis type 1 (NF1), leads to shorter nerve cell branches (right) in the back of the eyes of female mice. The shorter branches, not seen in male mice with the mutation, make the cells more vulnerable. This may explain why girls with NF1 are more at risk of vision loss from brain tumors. (Credit: David H. Gutmann)
Now, researchers at Washington University School of Medicine in St. Louis have identified a patient’s gender as a clear and simple guidepost to help health-care providers anticipate some of the effects of NF1. The scientists report that girls with NF1 are at greater risk of vision loss from brain tumors. They also identified gender-linked differences in male mice that may help explain why boys with NF1 are more vulnerable to learning disabilities.
“This information will help us adjust our strategies for predicting the potential outcomes in patients with NF1 and recommending appropriate treatments,” said David H. Gutmann, MD, PhD, the Donald O. Schnuck Family Professor of Neurology, who treats NF1 patients at St. Louis Children’s Hospital.
The findings appear online in the Annals of Neurology.
Kelly Diggs-Andrews, PhD, a postdoctoral research associate in Gutmann’s laboratory, reviewed NF1 patient data collected at the Washington University Neurofibromatosis (NF) Center. In her initial assessment, Diggs-Andrews found that the number of boys and girls was almost equal in a group of nearly 100 NF1 patients who had developed brain tumors known as optic gliomas. But vision loss occurred three times more often in girls with these tumors.
With help from David Wozniak, PhD, research professor of psychiatry, the scientists looked for an explanation in Nf1 mice (which, like NF1 patients, have a mutation in their Nf1 gene). They found that more nerve cells died in the eyes of female mice, and they linked the increased cell death to low levels of cyclic AMP, a chemical messenger that plays important roles in nerve function and health in the brain. In addition, Wozniak discovered that only female Nf1 mice had reduced vision, paralleling what was observed in children with NF1.
Two previous studies have shown that boys with NF1 are at higher risk of learning disorders than girls, including spatial learning and memory problems. To look for the causes of this gender-related difference, the scientists first confirmed that Nf1 mice had learning problems by testing the ability of the mice to find a hidden platform after training. After multiple trials, female Nf1 mice quickly found the hidden platform. In striking contrast, the male Nf1 mice did not, revealing that they had deficits in spatial learning and memory.
When the researchers examined the brain regions involved in learning and memory in the Nf1 mice, they identified biochemical abnormalities in the males but not in the females.
“We’re currently working to determine whether differences in the sex hormones are responsible for these abnormalities in vision and memory,” Gutmann said. “We’re talking about a disorder in young kids and in mice, where we normally would not expect sex hormones to play a major role, but we can’t rule them out yet.”
If hormones are responsible for these gender-linked distinctions in NF1, treatments that block hormonal function may be an option for use in patients with NF1, Gutmann added.
“Moreover, these studies identify sex as one important factor that helps to predict clinical outcomes, such as vision loss and problems in cognitive function, in children with NF1,” Gutmann said. “Further understanding of the interplay between sex and NF1 may change the way we manage individuals with this common brain tumor predisposition syndrome.”
(Source: news.wustl.edu)
Can you feel my pain? Middle-aged women sure can
Looking for someone to feel your pain? Talk to a woman in her 50s.
According to a new study of more than 75,000 adults, women in that age group are more empathic than men of the same age and than younger or older people.
"Overall, late middle-aged adults were higher in both of the aspects of empathy that we measured," said Sara Konrath, assistant research professor at the University of Michigan Institute for Social Research and co-author of an article on age and empathy forthcoming in the Journals of Gerontology: Psychological and Social Sciences.
"They reported that they were more likely to react emotionally to the experiences of others, and they were also more likely to try to understand how things looked from the perspective of others."
Konrath and colleagues Ed O’Brien and Linda Hagen of U-M and Daniel Grühn of North Carolina State University analyzed data on empathy from three separate large samples of American adults, two of which were taken from the nationally representative General Social Survey.
They found consistent evidence of an inverted U-shaped pattern of empathy across the adult life span, with younger and older adults reporting less empathy and middle-aged adults reporting more.
According to O’Brien, U-M doctoral student in social psychology, this pattern may result because increasing levels of cognitive abilities and experience improve emotional functioning during the first part of the adult life span, while cognitive declines diminish emotional functioning in the second half.
But more research is needed in order to understand whether this pattern is really the result of an individual’s age, or whether it is a generational effect reflecting the socialization of adults who are now in late middle age.
Transgendered bellbird found in New Zealand
Biologists at the Zealandia eco-sanctuary in New Zealand have spotted a bellbird that exhibits features and behaviour of both male and female members of the species.
The bird hatched in early 2011, and DNA testing then showed it as female, but since then its development has been rather different to normal female korimakos.
Normally, female bellbirds have a white feather pattern but the chick bean to show signs of the dark plumage normally seen on male birds. It also began to behave in a masculine way, not flitting between flowers like a female bellbird but instead moving with purpose, ready to defend its territory.
The bird’s calls are unusual too. It makes both male calls and the distinctive “chup chup” normally heard from females, but the latter are louder and more frequent that is normal.
Zealandia conservation officer Erin Jeneway told the Dominion Post: “There’s something we can’t pin down. We haven’t seen anything like this before”. Victoria University biologist Ben Bell added: “It could be due to a hormonal imbalance or it could be a reaction to shock or an incomplete moult — given the appearance and behaviour, any of those would be unusual though.”